Steel-founding



WWW/f J. G. MGROBERTS. STEEL FOUNDING.

Patented Spt. 5, 1893.

* UNITED STATES l PATENT OFFICE.

JAMES G. MCROBERTS, OF ST. LOUIS, MISSOURI.

STEEL-FOUNDING.

SPECIFICATION forming part of Letters Patent No. 504,361, datedSeptember '5, 1.893.

Application filed July 8,1893. vSerial Ilm/179,926. (No model.) i

Taal@ whom it may concern..

Be 1t known that I, JAMES G. McRoBERTs, of St. Louis, Missouri, havemade a new and useful Improvement in Steel-Founding, of

which the following is a full, clear, and exact description.

Between steel founding and ordinary iron founding this importantdifference exists in practice: About twice as much heat is required insteel founding as is in iron founding, and in consequenceshrinkage-strains to a corresponding degree have to be provided for.Furthermore, in view of the excessive. heat referred to, it has been thepractice to employ dry sand molds exclusively. 'The steam and gasescreated by the highly heated steel in casting it are generated sorapidly and profusely as to hitherto preclude the use of green sandmolds. But in the employment of dry sand molds this difficulty isencountered: the parts of a dry sand mold are incapable of yielding, oryielding sufficiently, to thesteel as it contracts in cooling, and inconsequence of this many forms cannot be cast. For instance, a structureof a vU-shape in cross section cannot be made satisfactorily; for thevarious sides in cooling draw toward each other and, meeting theresistive dry sand, are liable to, and frequently do, check and crack.Any form also having a shoulder projecting in a direction more or lesscrosswise to that in which the shrinkage occurs is liable to rupture ator in the vicinity of the shoulder.

As shapes such as referred to represent a large class of structureswhich it is desirable to form out of steel it is apparent that as theart of steel founding now exists the use of cast steel is materiallylimited. Moreover the expense of steel founding is considerablyincreased in having to use dry sand molds.

To prevent the checking and rupturing referred to it has been customaryto reinforce the casting, at the points therein where theshrinkage-strains have to be met, by forming upon the casting fins,brackets, and projections variously shaped according to the particularshape of casting being made. The integrity of the casting in this mannercan oftenv be preserved but the reinforce in question has to be removedfrom the casting after4 it has been made. Owing to the extreme toughnessof the steel the removal is an expensive operation, so expensive as tofrequently make it undesirable to make the casting. The improvementunder consideration pos .scsses several advantages some of which are asfollows: Wooden instead of iron liasks can be used; drying-ovens, asWell as the means for' transferring the iiasks to and from the ovens,are dispensed with, and the cost of operating the ovens obviated; thatspace upon the foundry iloor which is required for carriages for the drysand molds is saved for other purposes; but a single handling-of themold after it is made is required; the proportion of castings lost bychecking is largely if not entirely diminished; and the loss arisingfrom falling out due to excessive handling is prevented; the reinforcesare no longer needed except in quite exceptional instances, and the timeemployed in molding them in is saved; the loss arising from the burningand destruction of molds in the drying oven, something liable to occur,is prevented, and the cost of drying the mold is avoided, but further,and more especially, the improvement is desirable in that it greatlyextends the use of cast steel, and in that it materially cheapens theoperation of steel-founding.

The invention consists partly in the improved methodof casting thesteel,and partly .in the apparatus employed in carrying out the method, allsubstantially as is hereinafter set forth and claimed, aided by theannexed drawings, making part of this specification, in which- Figure lis a horizontal section of a suitable molding apparatus; duplicatecastings are arranged to be made and the viewincludes special cores forthe special castings being made; Fig. 2 a vertical section o'n the line2-2 of Fig. l; Fig. 3 a vertical section' IOO is shown; Fig. 8 avertical section on the line 8 8 of Fig. 7; and Fig. 9 a verticalsection n on the line 9-9 of Fig. 7.

The same letters of reference denote the same parts.

In carrying out the method under consideration the casting is made inasubstantiallygreen sand chamber or mold, but the molten metal isintroduced into said chamber or mold through a substantially-dry sandrunner or gate. I say substantially, for while an entirely-green sandmold, and an entirely-dry sand runner may be, and in most instances are,employed and are preferred, it is possible to have a portion or portionsof the moldwalls of dry sand where such dry portions do not oderresistance to the shrinkage of the metal in cooling to cause a rupturein the casting, and also to have a portion or portions of the runner ofgreen sand if they do not occur where the molten metal in beingintroduced into the mold would abrade or break away the gate or mold andthereby frustrate the formation of the casting but for such dry portionor portions. It is also necessary, in cases where a core is required,and the molten current enters the mold and impinges as a stream upon it,to have the core a dry sand one. What however characterizes the methodis the introduction of the metal by such means and in such a manner asto prevent particles of foreign matter, such as the particles of thewall of the gate through `which the lnetal is poured, from being carriedwith the metal into the mold, and as to prevent the generating of steamor gas either to break up the molten current and unfavorably aiect thecasting in respect to solidity, or to act to splinter ed portions of thegate to be borne along into the mold, and, on the other hand, the makingof the casting so that it shall be free to contract in cooling and whenmade to be integral.

An additional characteristic is introducing the molten metal into andthrough the mold so that it shall not break away or abrade any opposingpart of the mold walls, and so that it shall skin-dry the mold walls inadvance of its progress into the mold and enable the steam generated insuch skin-drying to be vented without interfering with the metal orcasting. Accordingly I prepare a wet sand mold of the desired shape, andIintroduce the steel thereinto by pouring it downward through a gatewhose descending portion, including a bottomportion at the lower end ofsaid descending portion, and upon which the metal drops, is of dry sand,and from said bottom-portion I conduct the metal horizontally, orhorizontally and upward, or substantially horizontally, or substantiallyhorizontally and upward, into the mold, and in delivering the metal intothe mold it is not allowed to drop as a body downward so as to cause themetal to bore into the bottom of the mold, but it is delivered eithersidewise or upward into the mold. The mold is vented freely (many morein consequence the castings as a rule are perfectly made. l

The described process may be illustrated by reference to the annexeddrawings.

The mold, A, Figs. l and 2, represents one adapted for the casting of apair of draw-bars B and B.

The gate is `shown at C. It has the descending portion c, the bottom cbeneath the descendng portion,and the branches, c2, c2 and c3, 08, whichconnect with the descending portion c and lead thence, two of them, c2,c2, to the chamber for casting the draw-bar B, and two of them, c3, c5,to the chamber for casting lthe draw bar B.

D and D represent dry sand cores suitably constructed and arranged forthe special work in question. The descending portion of the core is ot'dry sand as is also the bottom portion c. The mold is of wet sand. Themetal is poured downward through the gate-portion c and it flows thencethrough the various passages, 02, c3, into the chambers for forming thedraw bars, and as it enters said chambers it encounters the dry sandcores and it flows thence throughout the chambers and the castings arethereby made. Owing to the gateportions c, and c being of dry sand themetal does not generate any steam therein, nor does it out or bore intothat portion of thegate which is underneath the portion c. And even ifthe horizontal portions of the gate, the ones containing the passages c2and c3, were of wet sand such passages would by reason of the heat ofthe metal be skin-dried in advance of the movement of the metal. The drysand cores, D, D', receive the shock of the inflowing metal and are notabraded thereby. The metal after being cast cools without restraint andalthough there are various shoulders, b, b', b2, 85e., upon the draw barno rupture or check occurs at those points owing to the yielding natureof the mold.

Fig. 3 illustrates an arrangement where the metal is introduced througha horn-gate E, or a gate shaped to enable the metal, after dropping tothe lowest part of the gate, to rise into the chamber F of the mold.Provision for a riser is shown at f. The chamber F, in the presentinstance is for making a casting having no shoulders, and the view isintroduced more especially to illustrate the horn IOO IIO

gate, the gate having the descending portion r c and the bottom portione', and from such bottom portion the gate, in extending it to meet thechamber F, may be of wet sand but is preferably of dry sand like theportions e and e of the gate. For the metal after reaching the bottom ofthe gate acts to skin-dry the ascending portion, e2, of the gate andexpel the moisture thereof in manner similar to that in which theinterior surface of the mold is skin-dried.

Fig. 4 illustrates an arrangement where the metal is delivered through agate G sidewise into the mold H. A core I is shown. The core is of drysand, the mold is of wet sand, and the gate, at least the descendingportion g ald the bottom portion g thereof, is of dry san Figs. 5 and 6are respectively a side and a top view of a car truck bolster to be castaccording to the method under consideration. Said bolster incross-section is of an inverted U-shape, having the top J, the sides J',J2, and the ends J s, J 3, and the bolster is otherwise shapedsubstantially as shown.

The bolster is cast in a mold K, Figs. 7, 8 and 9. L represents the gateto be used in connection with said mold. It has the descending portionZ, the bottom Z, and passages Z2, Z2, connect the gate-portion Z withthe mold. Said last named passages Z2 Z2, connect i with the mold at anend thereof, and in depth column guides, M, of the bolster, specialcores,

N, N, are employed. While made tougher than the material of an ordinarywet sand mold they are not unyielding as a dry sand core is, and thusthey may be considered, in respect to the yielding quality of Vthe mold,homogeneous therewith. The gate L, so far as the descending and bottomportions thereof are concerned, is substantially of dry sand.

The mold K is substantially of wet sand, and

the above described advantages of a dry sand gate and a Vwet sand moldare, as in the case of the forms shown in Figs. 1, 3 and 4, obtained inthe casting of the bolster.

The illustrations here given will answer for any other structures moreor less analogous inform to those shown.

In using the terms dry sand i and wetsand I desire not to be restrictedto sand specifically, but wish it understood that any suitableequivalents may be substituted therefor respectively; that is, in theone case, refractory material suitable for making a gate through whichmolten steel can be poured downward without abrading the gate, orgenerating steam to cause what is termed explo- 'sion in the metal, and,in the other case, ma-

terial suitable for forming a mold of the yielding nature described, maybe used.

It is possible in the case of a quite shallow casting, and where aninterposed core may be used, to arrange the mold immediately beneath thegate instead of at the side thereof.

Irresp'ective of any special method or means for introducing the metalinto the mold a steel casting made in awet sand mold as described issuperior to a steel casting made in a dry sand mold. A steel castingmade in a dry sand mold has to be shaken out right away as otherwise itcannot be saved. But when made in a wet sand mold the casting can, andit is my practice to allow it to, remain in the mold for several hours,and, indeed, for an indenite time, and by reason of this the casting isnotably tougher than is a casting made from the same metal in a dry sandmold. The casting in cooling oif thus slowly in its own sand becomesmeasurably annealed. I claiml. The herein described improvement in theart of steel founding the same consisting in introducing the steelthrough a dry sand gate and forming the casting in a wet sand mold, asset forth.

2. The herein described improvement in the art of founding steel thesame consisting in introducing the steel through a drysand gate 'intoand through out a'green sand mold, and

so that the heat of the molten steel shall skin-dry the mold-walls inadvance of the progress of the metal through the mold.

Witness my hand this 6th day of July, 1893. JAMES G. MCROBERTS.Witnesses:

C. D. MOODY, A. BONVILLE.

IOO

